Have you thought about getting a hold of Tamiya america for the parts.
In the past I have had to call them for replacement parts.
They will charge you about ten bucks for a couple of parts trees and shipping.
you will need a credit card,the kit number,and the number on the trees that the parts you need are on.
If all go's well you will have your parts in a couple weeks.
That might be better than scratch building them which may cost you more time and as much at the hobby shop.
Plus you will have all those cool extra parts for your kit left over on the trees.
Good luck.....